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XHCI: Set the TRB_3_ENT_BIT on the final Link TRB, also.

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This should not be necessary due to a note in the specification,
but it seems some controllers may not obey that; see inline comment.

Possibly fixes the "mouse slowness" of #15115 that began following
the Event Data changes.
This commit is contained in:
Augustin Cavalier 2019-06-29 15:46:52 -04:00
parent 8bb337b5fe
commit 63895cb5f2
1 changed files with 11 additions and 3 deletions
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14
src/add-ons/kernel/busses/usb/xhci.cpp
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@ -842,7 +842,7 @@ XHCI::SubmitNormalRequest(Transfer *transfer)
//
// Note that we *do not* unset the CHAIN bit in this TRB, thus including
// the Link TRB in this TD formally, which is required when using the
// ENT bit. (XHCI 1.1 § 4.12.3 p241.)
// ENT bit. (XHCI 1.2 § 4.12.3 p250.)
td->trbs[td->trb_used - 1].flags |= TRB_3_ENT_BIT;
if (!directionIn) {
@ -1755,12 +1755,20 @@ XHCI::_LinkDescriptorForPipe(xhci_td *descriptor, xhci_endpoint *endpoint)
TRACE("_LinkDescriptorForPipe current %d, next %d\n", current, next);
// Compute link.
// Add a Link TRB to the end of the descriptor.
addr_t addr = endpoint->trb_addr + eventdata * sizeof(xhci_trb);
descriptor->trbs[descriptor->trb_used].address = addr;
descriptor->trbs[descriptor->trb_used].status = TRB_2_IRQ(0);
descriptor->trbs[descriptor->trb_used].flags = TRB_3_TYPE(TRB_TYPE_LINK)
| TRB_3_CHAIN_BIT | TRB_3_CYCLE_BIT;
| TRB_3_CHAIN_BIT | TRB_3_ENT_BIT | TRB_3_CYCLE_BIT;
// It is specified that (XHCI 1.2 § 4.12.3 Note 2 p251) if the TRB
// following one with the ENT bit set is a Link TRB, the Link TRB
// shall be evaluated *and* the subsequent TRB shall be. Thus, the
// TRB_3_ENT_BIT here *should* be unnecessary, as the last TRB in
// this TD proper should already have the ENT bit set. But at least
// some hardware, it seems, does not necessarily obey the note, so
// we add the ENT bit on the Link TRB, too.
#if !B_HOST_IS_LENDIAN
// Convert endianness.